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  1. Practice
  2. Artificial Intelligence
  3. Statistics and Machine Learning
  4. Day 5: Computing the Correlation
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Day 5: Computing the Correlation

  • davidtsukiyama1
     + 0 comments

    I am pretty sure this is correct but stdout is printing 'None' after I print out the coefficients. Additionally, computing statistics and machine learning related problems from stdin is silly. You simply do not manipulate data in this way in this kind of work, I do this type of work everyday; every question related to these topics should come with datasets that you load; not where you load each line from stdin or iterate over stdin, it is bizarre and irrelevant to this kind of work.

    *edit removing the print statements fixes the problem.

    import math
N = int(raw_input())

grades = []
for _ in range(N):
    grades.append([int(b) for b in raw_input().split('\t')])

m = [int(b[0]) for b in grades] 
p = [int(b[1]) for b in grades]
c = [int(b[2]) for b in grades]

def pearson(A, B, N):
    sumA = sum(A)
    sumB = sum(B)
    AB = sum([x*y for x,y in zip(A, B)])
    A_sq = sum([x**2 for x in A])
    B_sq = sum([x**2 for x in B])
    numerator = (N*(AB) - sumA*sumB) 
    denominator =  (math.sqrt((N*A_sq - sumA**2) * (N*B_sq - sumB**2)))
    print round(numerator/denominator, 2)
    
co1 = pearson(m, p, N)
co2 = pearson(p, c, N)
co3 = pearson(c, m, N)

print co1
print co2
print co3